Skip to main content

Full text of "Hetch Hetchy water supply"

See other formats


of the 




Hetch Hetchy Water Supply 


Member American Society, C. E. 














Digitized by the Internet Archive 

in 2012 with funding from 

California State Library Califa/LSTA Grant 



The past three years have been marked with strenuous activity toward the 
completion of the Hetch Hetchy Water and Power Project of San Francisco, which 
will be capable of furnishing the water supply for a population of 4,000,000 people 
when the construction storage works in the high Sierras have been completed. 

Five key dams stand completed, two of which — the O'Shaughnessy Dam and the 
Lake Eleanor Dam, hold back an aggregate amount of water greater than all the 
reservoirs of Los Angeles and San Diego massed together. 

Twenty miles of aqueduct tunnels have been completed in the high Sierras, 
while at the westerly end of the project Spring Valley water is being passed since 
September 12, 1925, through the Bay Crossing Aqueduct, 22 miles in length. The 
right-of-way for the aqueduct measures the width of the State and over this right-of- 
way the transmission towers have been erected which carry electric energy from the 
Moccasin Power Plant to the gates of San Francisco. 

Since August 14, 1925, the Moccasin Power Plant has been put into service 
and is now furnishing the greater portion of the power used to light the homes of 
San Francisco and drive the wheels of its factories. This has been made possible 
through a contract entered into with the Pacific Gas & Electric Company under 
which that company is employed as the temporary distributor of San Francisco's 
power output. The City received for the power delivered in San Francisco during 
the month of September, $182,426.97, or at a rate somewhat in excess of $2,000,000 
annually. On this basis the net revenue from the power, after paying operating 
expenses, and the $250,000 per annum to be received from the Spring Valley Water 
Company for the temporary use of the Bay Crossing Aqueduct, amounting to 
$1,900,000, will pay the interest at V/ 2 per cent on $42,000,000 of bonds, which is 
more than is now outstanding on the entire project. 

The gap remaining to be completed in the water supply portion of the project 
is the tunneling and laying of pipe from Moccasin Power House, through the 
mountains that mark the San Joaquin, Livermore and Santa Clara Valleys, to 
(rvington terminal. The work in the Foothill Division is now actually under way. 

The purpose of this outline is to enlighten the public generally concerning this 
•vater and power project, which is the greatest asset that San Francisco possesses, 
ind to these this report is respectfully submitted. 

M. M. O'Shaughnessy, 

City Engineer. 
San Francisco, California, October, 1925. 




By M. M. O'Shaughnessy, City Engineer 


AN FRANCISCO'S earliest water supply was taken from wells within 
the City, and ten million gallons daily are still obtained from this 
source. Such wells, however, soon became inadequate, and for a time 
it was necessary to import additional water in barges from across the 
Bay, and to distribute it by means of water wagons. 
In 1858, a company known as the San Francisco Water Works, instituted a 
pressure pipe water service, the source being Lobos Creek, which drains the north- 
westerly portion of the present City. A second company, the Spring Valley Water 
Works, brought water three and one-half miles from Islais Creek in 1861, and the 
following year increased its supply by taking from Pilarcitos Creek, 32 miles away. 
The two companies combined in 1865, under the name of the second, which, in 1903, 
reorganized as the Spring Valley Water Company. 

Under the single management, the sources were gradually added to; San 
Andreas and Crystal Springs reservoirs in San Mateo County were constructed, and 
pipe lines were built connecting them to the City. 

The Peninsular supply was added to in 1888 by the completion of two sub- 
marine pipe lines crossing San Francisco Bay and bringing in water from Alameda 
Creek. The capacity of the pipe line was increased in 1902,- and a booster pumping 
station added in 1913, bringing the present Spring Valley yield capacity up to about 
42 million gallons daily — twenty million from the Peninsula and twenty-two million 
from the Alameda County sources. 

The Spring Valley Water Company acquired, through all those years, over 100,000 
acres of land. After a complete survey in 1915, the City Engineer, with the approval 
of the Railroad Commission, as a basis for purchase by the City, excluded all but 
61,560 acres of land as being necessary for water purposes. In San Francisco 
County there remains for City use 913 acres, in San Mateo 22,817 acres, Alameda 
County 24,220 acres, and in Santa Clara 13,610 acres. 

On the 17th of April, 1922, an agreemnet, sanctioned by the Railroad Com- 
mission, was made between the Water Company and the City for the development 
of an additional 24 million gallons daily by the Company's reconstruction of the 
Calaveras Dam, Niles Canyon concrete conduit, and 16,000 feet of 44-inch pipe 
from Niles to Irvington. The City agreed to spend $5,000,000 of the Hetch Hetchy 
funds in building 22 miles of conduit, consisting of 5-foot diameter pipe — capacity 
for delivery under Hetch Hetchy conditions of 43 million gallons daily — from 
Irvington, through Pulgas Tunnel, to Crystal Springs Reservoir. As consideration 
for the lease of this conduit by the Water Company the City receives an annual 


rental of $250,000. Under the same agreement, the City holds an option good until 
December 31, 1933, to purchase the Water Company's system and the lands enumerated 
above for $38,000,000. 


The Hetch Hetchy Project is one to provide an adequate municipal water supply, 
evolved by the City and County of San Francisco, after a thorough and comprehensive 
study of all possible sources. The general plan contemplates the collection and 
storage of waters of the Tuolumne River and its tributaries near their sources in 
the Sierra Nevada Mountains, and the transmission of those waters across the San 
Joaquin Valley and through the Coast Range Mountains for delivery to the 
City of San Francisco and its environs; due advantage being taken of appropriate 
drops in the conduit routes for the generation of the maximum quantity of hydro- 
electric power which can be economically developed. 


The project had its beginning back in 1901, when the Mayor of the City filed 
water appropriations on the Tuolumne River and its tributaries, Cherry River and 
Eleanor Creek. These appropriations were kept alive by preliminary development 
work until a permit was obtained from the Federal Government for the acquisition 
of storage reservoir sites situated on public lands within the limits of the Yosemite 
National Park (not Yosemite Valley). This was granted by Secretary of the 
Interior Garfield in 1908 relative to lands and waters tributary to the Tuolumne 
River in the northern part of the Park and twenty miles distant from the Yosemite 
Valley proper, which latter is drained by the Merced River. Having secured this 
permit, San Francisco proceeded to acquire, at an expense of $1,915,000, all privately 
owned lands in the Hetch Hetchy Valley and the rights and holdings of William 
Ham Hall, John Hays Hammond and others on the Tuolumne and Cherry Rivers and 
on Eleanor Creek, a tributary of the Cherry. With the accession of the Ballinger 
administration in the Interior Department, a movement was started by certain coteries 
of so-called "nature-lovers," and others, to revoke that portion of the Garfield permit 
relating to the Hetch Hetchy Valley, which was the largest of the proposed reservoir 
sites. Secretary Ballinger went out of office after having issued an order directing 
San Francisco to show cause against this revocation. President Taft ordered an 
investigation and report by a Board of United States Army Engineers, consisting 
of Colonel John Biddle, Lieutenant-Colonel Harry Taylor and Major Spencer Cosby. 
This board of engineers examined exhaustively all alternative sources of supply 
which had been suggested as available for San Francisco's use, including the 
Stanislaus, Calaveras, Mokelumne, Cosumnes, American, Yuba, Feather, McCloud, 
Sacramento, Eel, and San Joaquin Rivers, and the local sources of the Spring Valley 
Water Company. The Army Engineers' report, made to Secretary Fisher, Mr. 
Ballinger's successor, under date of February 19, 1913, recommended the use of 
the Hetch Hetchy Valley and the Tuolumne supply as being not only the most 
available but the cheapest and most economical for the City's use and affording the 
greatest hydro-electric development possibilities. Previous to the report of this 
board of engineers, the City had an exhaustive examination of all available sources 
made by John R. Freeman, an engineer of national repute, associated with the water 
supplies of Boston and New York. He strongly recommended the Tuolumne source 
as the best and outlined the scheme of development which, with some necessary 
modifications, is now being followed. 

After taking testimony and examining all reports submitted, Secretary Fisher 
gave it as his opinion that Congress alone had the power to grant the privileges 

sought by the City. After a great deal of argument before Congress, the Hetch 
Hetchy grant was passed by both Houses and signed by the President on December 
19, 1913. This act was framed on the recommendation of Secretary Lane of the 
Interior Department and Secretary Houston of the Department of Agriculture, and 
by it Congress (Stats. 1913, p. 242) granted forever to the City rights in 420,000 
acres of the public domain. 

The water rights have, from their inception, been carefully protected and title 
to the same is fully vested in San Francisco under the provisions of the Civil Code 
of California. Antecedent to this, on January 14, 1910, the people of San Francisco, 
by a vote of 32,886 for and 1,609 against, authorized the issuance of $+5,000,000 of 
bonds for the construction of the project. 

Actual work was commenced as soon as the Congressional grant was obtained. 
Surveys were completed, many miles of wagon road were constructed, a standard 
gauge railroad 68 miles long was located and built, the floor of Hetch Hetch Valley 
was cleared of timber, a sawmill was installed and put in operation, diamond drill 
borings were made at the main damsite and along the line of the tunnel aqueduct, 
a construction power plant was built, together with a dam at Lake Eleanor, storing 
nine billion gallons to carry the plant through the dry season, and an aqueduct to 
supply the plant with water. Twenty-two thousand volt transmission lines connect 
it with all working points on the tunnel aqueduct, camps and warehouses. Head- 
quarters buildings were constructed, and work has been completed on the Mountain 
Division, including the O'Shaughnessy Dam at Hetch Hetchy, the Mountain Aqueduct, 
Priest Dam, power tunnel, pressure pipes, Moccasin Power House, and tower line 
for transmission of electrical energy to San Francisco as far as Newark. 

During the period of the war the City carried on work with a force of from 
400 to 500 men, with due care always not to interfere with the selective draft or 
the nation's need for materials and equipment. Progress was necessarily not as 
rapid as would otherwise have been the case. Sound economic reasoning dictated 
that the Mountain, or power-generating, division, of the project be completed first, 
in order that the burden upon San Francisco's taxpayers of paying interest during 
construction might be reduced by revenue from power at the earliest possible 
moment. The dominant purpose of the project is, however, water supply, and 
every effort must be made to complete the water conduits without unnecessary delay 
in order to remedy the water shortage from which San Francisco has long been 


The space afforded in this resume suffices for only a brief description of the 
principal engineering features of the project. For convenience the work has been 
divided into ten divisions, known as the Lake Eleanor, Hetch Hetchy, Mountain, 
Priest, Moccasin, Foothill, San Joaquin, Coast Range, Bay Crossing and Peninsula 
divisions. Surveys, geological and engineering studies have so far been conducted 
over the entire work and construction done on all divisions except the San Joaquin 
and Coast Range. 


The 'Hetch Hetchy development is one of the activities of the Department of 
Public Works of the City and County of San Francisco. The City Engineer is 
Chief Engineer of the project, and the Chief Assistant Engineer has direct charge 
of the work. Two construction engineers, located at Groveland and at Palo Alto, 
report to the Chief Assistant Engineer. Legal matters are handled by special counsel 
and rights-of-way by a right-of-way agent. 

M. M. O'Shaughnessy, City Engineer 

The staff consists of: 


M. M. O'Shaughnessy, City Engineer Chief Engineer 

N. A. Eckart, Chief Assistant Engineer 

City Office Engineers 

L. W. Stocker Assistant Engineer 

R. P. Mcintosh Hydraulic Engineer 

R. J. Wood Structural Engineer 

P. J. Ost Electrical Engineer 

E. P. Jones Mechanical Engineer 

Construction Engineers 

L. T. McAfee Construction Engineer, Groveland 

C. R. Rankin Construction Engineer, Palo Alto 

L. A. McAfee Assistant Engineer, Groveland 

J. H. Ryan Assistant Engineer, Groveland 

A. J. Wehner Assistant Engineer, Groveland 

L. B. Cheminant Assistant Engineer, Groveland 

A. B. Johns Assistant Electrical Engineer, Groveland 

General Office Staff 

Robert M. Searls Special Counsel 

Jos. J. Phillips Right-of-Way Agent 

H. W. Kephart Purchasing Agent 

The following are among the experts who have acted as consultants at different 
times on the project: 

Frank G. Baum Electrical Engineer 

Dr. Wm. F. Durand Mechanical Engineer 

Dr. Jas. C. Branner Geologist 

John D. Galloway Civil Engineer 

Professor Chas. D. Marx Civil Engineer 

Professor Charles Wing Civil Engineer 


In starting any business enterprise it is of the highest importance that the 
income which is to support the enterprise should commence as early as possible, so 
that the interest and other fixed charges on the investment shall not be a dead- 
weight on the investors any longer than absolutely necessary. 

In the case of the Hetch Hetchy Project, it required only the construction of 
the main storage dam and the upper 20 miles of the aqueduct to reach the 1300-foot 
power drop at Moccasin Creek. Hence the decision was made to concentrate all 
energy and financial resources on the works above the Moccasin Creek power plant 
site for the two-fold purpose of developing and protecting our water rights and 
producing an income from hydro-electric energy that could be applied to reduce the 
burden of interest and bond redemptions during the later construction of the aqueduct 
between Moccasin Creek and San Francisco. 

With the greatly advanced prices of labor and materials resulting primarily 
from the World War, exceeding pre-war prices by 70 per cent, and the wider scope 
of the project as evolved under the Hetch Hetchy grant, and also on account of the 
necessity of selling bonds at a substantial discount for several years, the completion 
of the units mentioned will exhaust the funds realized from the $45,000,000 bond issue 
of 1910. The completion of the aqueduct will require money to be obtained from 
further issuance of bonds, but the revenue from power sales and from the Spring 
Valley Water Company will meet, to a very large extent, the interest on the new 
bonds; so the wisdom of the course adopted is thus apparent. 

Construction Begun 

Hetch Hetchy Water Supply Contract No. 1, awarded July 8, 1914, covered the 
grading of nine miles of 22-foot roadway from Mather to Hetch Hetchy, which 
hitherto had been accessible only by trail. The road was completed in March, 1915. 

A diversion tunnel 20 feet in diameter, to deflect the main Tuolumne River, was 
then excavated in the south wall of the Hetch Hetchy gorge around the damsite. 
Timber clearing was commenced in the reservoir area, and borings were made at 
the damsite to determine the depth to bedrock in the river bottom. 

Up to the present date, 106 public contracts for all features of the work, 
aggregating $25,000,000, have been awarded by the Board of Public Works after 
appropriations have been made by the Board of Supervisors, based on open bidding 


on plans and specifications prepared by the City Engineer. There has been no 
breath of scandal or insinuation of any kind relative to any of these contracts or 
any other phase of the work. 


To transport equipment and materials to Hetch Hetchy Dam, the aqueduct 
tunnels and the power plant, a standard gauge railway was built on grades not 
exceeding 4 per cent and on curves not exceeding 190-foot radius, extending along 
the entire upper end of the work in the foothill and mountain divisions. The 
Hetch Hetchy Railroad, 68 miles in length, connects with the Sierra Railway at 
Hetch Hetchy Junction, 26 miles from the town of Oakdale, and extends to O'Shaugh- 
nessy Dam. 

Hetch Hetchy Ra 

I. Tuolumne River Bridge 

Starting at Hetch Hetchy Junction, at an elevation of 935 feet, the route leads 
across rolling country and descends into the Tuolumne River Canyon to 600 feet 
elevation. It then follows up the river, crossing it on a steel bridge below Jackson- 
ville. At Moccasin Creek a steep climb begins, and continues until elevation 3070 is 
attained at mile 26, near the headquarters town of Groveland. From this point 
east the line follows generally the dividing ridge between the Tuolumne and Merced 
Rivers. Thence the general elevation increases until at mile 62 the summit is reached 
— Poopenaut Pass — at elevation 5064. Six miles of continuous descent on a 4 per 
cent grade complete the 68 miles to Damsite, where the elevation is 3870 feet. 
The last nine miles of the railroad was built on the roadbed previously graded and 
used as roadway. 

The railroad serves the working points of the 30 miles of main aqueduct east 
of the Sierra Railway, the Moccasin power development, and the City's sawmill, 

some directly, others through short spur tracks, tramways, or motor truck hauls. 
Haulage from the railroad is generally in the downhill direction. 

Snowplow at Mather Station, 
Hetchy Railroad 

Early Intake from Heteh Hetchi 

The railroad was commenced in 1916 — with over 1,000,000 cubic yards excava- 
tion, and completed in October, 1917. It was operated from July, 1918, to February, 
1925, as a common carrier. Freight rates were on a basis of 12^ cents per ton 
mile for carload lots for all freight except lumber and livestock, on which commodity 
rates were established. The basis of passenger fares was iy 2 cents per mile. 

The cost of construction of the railroad was about $3,000,000. The early use of 
the road enabled the City to complete the O'Shaughnessy Dam in April, 1923, in 
three and one-half years, and thereby gave San Francisco priority to the flood 
waters of the Tuolumne River. 

The completion of the Don Pedro Reservoir by the Turlock and Modesto 
Irrigation Districts necessitated the relocation of the Hetch Hetchy Railroad at the 
Six Bit Gulch crossing, the old trestle at this point being four feet below the flow 
line of the reservoir. The trestle was replaced by a nine-span plate girder bridge, 
585 feet long, 15 feet higher in elevation than the old trestle. The reconstruction 
of this bridge and the relocation of adjacent stretches of track were made on request 
of, and were paid for, by the two irrigation districts. 

Sawmill machinery was purchased in August, 1915, and a sawmill erected at 
Canyon Ranch, five miles from Hetch Hetchy. After six million board feet of 
lumber had been sawed at this location, the supply was exhausted and the sawmill 
moved to Mather. At Mather it continued to operate until the winter of 1923-1924, 
when, having served the needs of the present construction, its operation was dis- 


Construction Power House at Early Intake. General view showing forebay 
flume, penstock and building. 

continued. Lumber from the mill was used for concrete forms, camp buildings, 
flumes, tunnel timbering, and miscellaneous structures. High-grade lumber, such as 
sugar pine and white pine, not required in the City's work, was traded to privately 
operated mills to advantage for cheaper woods. A total of 21 million feet B. M. 
was cut. 


To operate construction equipment in the mountains, a 3000 K. V. A. power 
plant was installed near the mouth of the Cherry River. The construction was 
commenced in the summer of 1916, and completed, ready for operation, in June, 1918. 

Water for this installation is diverted from Cherry Creek into a conduit of 200 
second feet capacity, 3.3 miles long, consisting of 1.2 miles of tunnels, 1.1 miles of 
flumes, and 1 mile of concrete lined canals. The power house contains three turbines, 
operating under a maximum head of 345 feet, fed by a 42-inch pipe line 530 feet 
long, each direct connected to a 2300 volt, 1000 K V. A. generator. Power is 
transmitted at 22,000 volts 11 miles east to O'Shaughnessy Dam and 22 miles west 
to Moccasin Creek, supplying intermediate substations along the line. Since the 
completion of Moccasin power plant the Cherry aqueduct has been extended one- 
half mile to Early Intake Diversion Dam so that the Lake Eleanor water can be 
passed through the main aqueduct to Moccasin. 

This system has furnished power for all the Hetch Hetchy Water Supply 
activities as required, except the main sawmill drive; and surplus power has been 
sold to the Pacific Gas & Electric Company through a connection at Priest. Two 
interruptions of power operation from February 25, 1922, to April 21, 1922, and 
from February 25, 1923, to March 14, 1923, resulted from landslides carrying away 
portions of the open concrete lined canal, and one from November 28, 1921, to 
December 18, 1921, from a shortage of water. Those breaks caused serious loss in 

Power House at Early Intake. Interior showing three Pelton Francis 
turbines direct-connected to 1000 K.V.A. generators 

the continuous operation of the work until a dependable outside standby service was 
connected up. During such interruptions power was drawn from the Pacific Gas & 
Electric Company system to supply the westerly end of the work. 


To permit the operation of the power plant during the low water season, it was 
necessary to develop a certain amount of storage at Lake Eleanor. The construction 
of Lake Eleanor Dam was commenced in August, 1917. It was put in service in 
June, 1918. The dam is 1260 feet long and 70 feet in maximum height. It contains 
11,640 cubic yards of concrete, heavily reinforced. It is of the buttressed arch 
type, with several original features developed by the City Engineer's studies. 
There are 20 arches, each with a span of 40 feet. These arches are on an incline 
of 50 degrees to the horizontal and are supported by buttresses. The dam is curved 
in plan. One interesting feature to the engineer is that the cross-section of the 
arches follows a circular arc on a horizontal plane, and an elliptical arc on a 

Lake Eleanor multiple arch dam which impounds 27.S00 acre feet 

normal plane, which is the reverse of the usual construction heretofore used in this 
type of dam. Over the entire length of the dam is a reinforced concrete roadway, 
12 feet wide. 

The stored water is withdrawn through two 24-inch sluice gates, placed on 
the face of the dam. 

The dam was completed late in 1918, but had already been put to use for 
storage of water to operate the Lower Cherry power plant. The entire cost of the 


O'Shaughnessy Dam. Deepest point of excavation for foundation, 118 feet below bed 
Tuolumne River. Outline of dam shown by white lines on the rock 

structure, including a 12-mile wagon road from Hetch Hetchy costing $28,000, was 
about $320,000. 

The flow line of the reservoir created by the dam is at elevation 4660 feet, 
and its capacity is about 27,800 acre-feet, or nine billion gallons. This quantity is 
only a small part of the annual runoff from the Lake Eleanor watershed, and the 
reservoir is filled each year early in the flood season. 


The contract for the construction of the first installment of the O'Shaughnessy 
Dam across the Tuolumne River at the outlet of Hetch Hetchy Valley, was awarded 
after open bidding August 1, 1919, to the Utah Construction Company. 

The dam is of the arched gravity type — 700-foot radius — built of cyclopean 
concrete (concrete in which are imbedded large blocks of stone ranging in size from 
about one cubic foot to five or six cubic yards). 

When the water supply or electric power requirements demand, the dam will 
be raised to its ultimate height and thickness. So great is the present-day demand 
for hydro-electric power, and so constantly is it increasing, that the completion of 
the last addition will probably be governed by power needs rather than consideration 
of the water supply. 

All foundation work below stream level for the ultimate structure has been 
completed with the present construction. 

When it becomes necessary to add to the reservoir capacity developed by the 
initial dam, the dam will be brought up to its full ultimate size by adding a thickness 
of 80 feet on the downstream face of the initial dam and building up 85 feet higher. 
This will make available 80 feet additional depth of reservoir, and will make the 

messy Dam. The heavy valve section in the center is full thickness for the 
tlam when built to its ultimate height 85 feet above the present crest 

lake 300 feet deep at the dam. The total height of the dam above the foundations 
will then be 430 feet. This is higher than any dam now in existence. 

The initial dam has a height above the original stream bed of 226.5 feet, and 
a maximum height above foundations of 344.5 feet, and contains 398,516 cubic 
yards of concrete. The length on the crest is 605 feet and the thickness on the crest 
is 15 feet. The thickness of foundation is 298 feet. The present wasteway consists 
of 18 spillways of the siphon type, discharging over the downstream face of the 

The floor of Hetch Hetchy Valley has been cleared of timber, in order to protect 
the impounded waters from contamination due to the decay of submerged timber. 

Valves for Outlet System 

Valves to control the discharge of water for irrigation and domestic use through 
the dam as required, have been installed at various levels. Openings, designated as 
supply pipes, supply wells, and discharge conduits, have been cast in the concrete as 
the structure was built. 

The valves consist of the following: 

Six 5-foot balanced needle valves; 
Six 3-foot balanced needle valves ; 
Six 47-inch by 90-inch slide gates ; 
Six 33-inch by 42-inch slide gates. 

The valves and their appurtenances comprise over two million pounds of 
metal of high-grade design, and cost nearly $700,000. 

On each opening through the dam there are two controls. The water is admitted 
through the hydraulically operated slide gate to the supply well and from there the 
required flow is regulated and discharged by the balanced needle valves. These 
valves are of the latest type of hydraulically balanced valve which permit manual 
control of a plunger weighing five tons, under a high head of water. The water 
discharges in an annular ring surrounding the plunger. 

The six 5-foot balanced valves and the six 47-inch by 90-inch slide gates are 
installed in the main portion of the dam, being set in the concrete as the structure 
advanced. Three of the 3-foot balanced valves are installed on the lower side of 
the dam at elevation 3625, in a special valve house, and have three 33-inch by 42- 
inch gates installed in the dam in connection with them. Three 36-inch needle 
valves and three 33-inch by 42-inch slide gates are installed in the concrete plug 
in the diversion tunnel and permit draining the reservoir to its lowest levels. All 
sluice gates can be made accessible for repairs by closing the inlet tunnels by means 
of steel shutters in concrete slots. 


The temporary spillway of the initial dam consists of 18 siphons, each 4 feet by 
10 feet at the throat, and placed in three series at slightly different levels. The 
siphon openings are heavily reinforced with steel. Each siphon has a capacity of 
approximately 1,000 cubic feet per second. The spillway has operated successfully 
since May 25, 1923, when the reservoir first reached its flood limit. The water 
discharging from the siphons down the steps on the back of the dam forms a water- 
fall of imposing appearance. 

It is the plan, on the final completion of the dam to full height, to bypass the 
floods through canals and tunnels at either end past the abutments of the dam so 
as to clear the structure altogether, and plug the existing siphons with concrete. 


Roadway on Dam 

The top of the dam is finished with a 17-foot roadway, on the sides of which 
are placed precast concrete railings, which add an artistic finish to the structure. 
A concrete girder bridge connecting the dam to the Eleanor road harmonizes 
with the main structure. The east abutment of the bridge is on roller bearings to 
provide adjustment to meet temperature changes and consequent movement in the 
arched dam. 

* J 





Department of Public Works. ////// /if\/ yvv. M4AU*h, „ 

approved, UM/\Uv* jL,i ^r^^\/ City Engineer 


SCALE As shown DATE June IZ 192^. 


A 287, 

Construction Methods 
In order that the foundation of the dam might be constructed in the dry, a 
rock-filled timber crib dam was built above the location of the main dam, and a 
concrete backwater dam 800 feet downstream, thus passing the water around the 
damsite through the diversion tunnel which had been enlarged to 23 feet by 25 feet. 
Excavation down to 65 feet below streambed was accomplished with steam shovels 
and dump cars; below that level derricks and skips were used. 

At elevation 3439 at the downstream toe, bedrock was encountered and a concrete 
retaining wall, 31 feet in height, was built, sealing off all seepage into the lowest 
portion of the foundation. At the upstream toe, on reaching an elevation of 3435 
feet, a cofferdam was sunk to bedrock, elevation 3399, and a concrete retaining wall 
was poured, cutting off practically all seepage into the excavation. 

After removing all material overlying the granite bedrock, this was roughened 
to receive the concrete. A sand-blast was used in places to roughen the glazed and 
polished surfaces of the pot holes in the water-worn rock formed by pre-historic 
cascades from ancient glaciers. This provided a clean, rough surface for bonding 
the concrete. 

Concrete was placed with chutes from a wooden, four-compartment hoisting 
tower, 375 feet high, built on the south side of the canyon. After the forms were 
removed, a coating of gunite was applied to the upstream face. 

During the cold weather period each year from December to March, a heating 

Hetch Hetchy Reservoir. View east showing central three miles of r 
Rock on right, rises 1SO0 feet above floor of valley 

plant, consisting of a large steam boiler and circulating pipes, was installed to 
prevent the concrete from freezing. 

Large stone, or plum rock, was placed in the cyclopean concrete to an amount 
not exceeding 8 per cent of the mass. 

Rock for concrete was crushed in a plant located on the valley floor upstream 
from the damsite. Sand was excavated about three miles upstream from the 
damsite and hauled to the work on a 3-foot gauge construction railroad, with ten 
locomotives, and there screened, stored and reconvened to the mixers. Plum rock 
was taken from the talus slopes on the north side of the valley and hauled one 
mile to the dam on flat cars. Cement in bulk was unloaded from cars on the 
Hetch Retchy Railroad into a bin above the dam, and conveyed to the mixers by 

Concrete placing began in September, 1921, and finished in February, 1922; 
398,516 cubic yards being placed. 

The dam was completed in May, 1923. The cost of construction by the Utah 
Construction Company was $6,121,000. On May 24 the reservoir was completely 
filled and the siphon spillway began discharging the flood waters. 

A turbine generator and storage battery were installed in the bypass tunnel to 
supply power to meet local requirements at O'Shaughnessy Dam when the existing 
transmission line from Early Intake to the dam is removed. 


The water released from Hetch Hetchy reservoir flows, for the present, 12 miles 
down the Tuolumne River to Early Intake Diversion Dam. Eventually, it will 
flow through a 12-mile tunnel and a power house developing 60,000 horsepower 
and be discharged above the diversion dam. The water from Lake Eleanor, which 
now flows down Eleanor Creek, Cherry River, and the Lower Cherry aqueduct 
about 10 miles to the diversion dam, eventually will be carried in an aqueduct 
about 11 miles long to a power house in the Tuolumne River Canyon about one 
mile above Early Intake, where 40,000 horsepower will be generated. The water 
released from the plant will flow down the river channel with the water from 
Hetch Hetchy and be diverted into the tunnel aqueduct which begins at Early Intake. 

The diversion dam consists of a thin concrete arch 262 feet long and a concrete 
spillway 130 feet long. On the left bank is the aqueduct intake tower with gates 
regulating the flow of water for San Francisco's use. Water in excess of that 
diverted to San Francisco and necessary to supply the Turlock and Modesto 
irrigation districts will pass over the spillway to flow down the Tuolumne River 
about 40 miles to Don Pedro Reservoir. 

The diversion dam has an upstream radius of 100 feet. Thickness at crest at 
elevation 2356 is 6 feet, at base 16 feet. Height above river-bed is 55 feet and the 
base extends 26 feet down to solid granite. On the south, the arch abuts the granite 
canyon wall; on the north is a concrete block containing 3611 cubic yards. From 
this block the spillway extends northerly, divided by piers into five sections, each 
23 feet long, in which automatic radial gates have been installed, whose function is to 
maintain the water surface at elevation 2346, or 5 feet above the lip of the spillway. 
Tunnel invert at inlet is at elevation 2326 feet. A siphon arrangement automatically 
lowers these gates to pass excess floods and allows them to rise after the flood has 
subsided. In constructing the arch section of the dam, two vertical openings with 
keyways 18 inches wide, were left at the points of approximate zero bending 


Moonta/n Dws/on 
Tonne/ '. /g.g m/'/es 
to fh/est ffeservo/, 


Crest ofJJam Z3J6 ft. 

*- 3ottom of /vt/natof/bo ZZ75 ■ 

% Funnet /nvert 2.326 • 

(^ So, >//H>ay £/p Z34I » 

tVorma/ M&ter Jt/rface Z344> ■■ 





Scale of Feet 
Department of Public Works, approv 


SCALE..*o 4. iszs 


-City Enoinkcr 

A 280. 

moment until the dam had taken final set. Then in the extreme cold weather, when the 
dam had received final set, these keyways were filled with concrete. 

The gate tower at the intake is equipped with fixed grillage outside, to catch 
heavy refuse; and wire mesh, manually operated, traveling screens inside, to catch 

tunnel to Prie 

nn. View up Tuolumne River. Flume on left discharges water 

Sherry River. Gatehouse on right is the inlet to the 18.8-mi" 

. Spillway on left, with automatic gates, bypasses flood waters 

leaves and light refuse. Sand chambers in front of the screens discharge through 
the dam. There are 9 sluice gates, 4 feet by 5 feet, 5 in the lower tier and 4 in 
the upper. These are set in a thin reinforced concrete arch of 16 feet radius abutting 
on the rock wall of the canyon. A concrete house covers the operating wheels, 
screen mechanism, etc., the whole structure being protected from falling rocks from 
the adjacent mountainside by a reinforced concrete guard wall on the uphill side 
of the intake. The dam, spillway and gate structure contain 16,564 cubic yards of 

Mountain Division Tunnels 

The Mountain Division Tunnels extend 18.8 miles from here to Priest Reservoir. 
The first half mile of tunnel skirting under the canyon wall is 14 feet 3 inches high 
by 13 feet 4 inches wide, with top arched to 6 feet 8 inches radius, bottom to 20 
feet 5 inches radius, has 166.5 square feet neat excavation, and is unlined, except 
for a few short stretches. The next seven miles, also unlined, is excavated to 
13 feet 6 inches high by 13 feet 4 inches wide, with top arched to 15 feet radius and 
bottom to 20 feet 5 inches, with neat arta 167.8 square feet. This section is 
interrupted near mile No. 5 by 225^4 feet of 9 feet 6-inch diameter riveted steel 
pipe, which carries the flow across the south fork of Tuolumne River. The pipe is 
a continuous beam of four unequal spans, the longest being 74 feet across the main 
channel, and is supported on concrete piers whose reinforcmeent extends into holes 
drilled in the bedrock. An expansion joint is introduced at the point of contraflexure 


- a) 

nearest the upstream anchor. The pipe is covered with heavy timber to prevent 
damage from rocks falling from the cliffs above. 

The remainder of the tunnel, about 11.3 miles, is lined throughout with l:2%Ay^ 
concrete with minimum thickness of 6 inches. 

This tunnel is of horseshoe shape 10 feet 3 inches high by 10 feet 3 inches wide, 
of 87.94 square feet net area inside of lining. The rock encountered consisted of 

sect/on /, coA/cffrrz t_/t\tf£>. 

Anv, ins/ate concrete 07.94 if ft 
• excavat/en, ant/mbered /of. 63 
, timbered t33.f * 
fifcaraf/on perfoof: 

L/ntimberea '■ ^3.91 z cuy 
Umbered -« ?■* 
Cone re /e per /do/ 
t/n timbered '■ .655 
Timbered - / .39 
Actt/a/ ai/eraqe for 
//.3 mi/es - Z.04 

y5fCr/OA/S , Mt/M£0. 
Area , sq.ft. /6&5 
Excavation per 

foot, a/ yds 6.17 
Note - This section used 
on/y for the "ft/Version 
Tcnne/, joj~/ ft. /or?^ t 
at fc/r/y //jfake . 

SECT/ON 'of-, t/MJN£D. 

Area ■ ■ 1 67. s sq.ft. 

"ion per foot- 6.ZI cuydj. 





Department of Public Works, approved 




:liJ^A s ^^^. 

SCALE_.~jnch.£.L_fDot... DATE Jure 9,1925. 

City Engineer 

A 282 


diorite, quartzite, slate and amphibolite schist. The tunnel with a grade of 0.00155, 
or about 8 feet per mile, has a capacity of 620 second feet. 

Excavation was carried on from 12 working faces: one at each end portal, one 
on each side of the stream crossing, four from two adits and four from two shafts. 
The first heading was begun at the south fork Tuolumne River crossing, July 7, 
1917, proceeding easterly. Big Creek shaft was opened in February, 1918, and 
tunneling begun from 575 feet below the collar in August, 1919. The shaft was 
646 feet deep. Second Garrote shaft, 786 feet deep, was begun in November, 1918, 
but encountered excessive amounts of water as high as 2,000 gallons per minute, 
which delayed its completion until December, 1922. The last connection in driving 
the 18.8-mile tunnel was made between Big Creek shaft and Second Garrote shaft 
on November 26, 1923. 

Muck car trains in the tunnels were hauled by electric storage battery locomotives. 
Electric mucking machines were used at all headings except while working out from 
Big Creek and Garrote shafts, which were too small to allow the convenient 
passage of the electric machines. At these headings smaller air operated mucking 
machines were used. A spare machine was maintained at each camp to insure 
continuity of service. Electrically driven air compressors and blowers were used 
at all the camps. At Second Garrote shaft a steam driven air compressor was 
maintained for standby service to insure against failure of electric power supply. 

The rate of progress varied according to the formation, from 300 to over 700 
feet per month. The best record for one month was 776 feet, made from the Priest 
(west) portal of the tunnel. This established a new United States speed record for 
hard rock tunnel driving. 

Tunnel lining was begun with one plant on March 20, 1923; after April, 1924, 
two plants were working and completed the lining in May, 1925. The total distance 
lined is 60,630 feet. 


At the west tunnel portal at elevation 2170 the water enters Priest Reservoir, 
created to provide forebay capacity for the fluctuating demand of the Moccasin power 
plant. The reservoir was made by constructing an earth fill dam with concrete core 
wall across Rattlesnake Creek. This forebay reservoir contains 2350 acre feet, or over 
two days' flow of the tunnel. Priest Dam is 1160 feet long and 145 feet high. Crest 
width at elevation 2245 is 20 feet. The dam is 660 feet thick at its base and contains 
717,283 cubic yards of earth and rock fill and 17,043 cubic yards of concrete in the 
core wall, which extends 15 feet deep into bedrock. To provide a certain degree 
of flexibility the core wall is divided into panels 50 feet long by 16 feet high, water 
stops of 16 gage copper being placed in the joints between panels. Some 27 tons 
of copper are used in the structure for this purpose. 

The embankment consists of rock spoil from the tunnels placed in the up and 
downstream toes, earth fill placed by hydraulic methods and earth fill placed by 
dump cars from steam shovel and sluiced into place by water jets. The slope of the 
upstream face is iy 2 to 1 ; downstream face is 2 to 1 slope except the rock toe, 
which is l}i to 1. The upstream face is riprapped to prevent erosion from wave 

A concrete lined spillway 40 feet wide, with lip at elevation 2240, protects 
against overtopping. An outlet and drainage tunnel 6 feet in clear diameter, with 
inlet at elevation 2120 feet, was driven through the solid rock of the east abutment 
and lined with 12 inches of concrete. Valves in the tunnel are reached by a vertical, 


Priest Dam. View down Rattlesnake Creek. Track in left center marks outlet of 
18.8-mile tunnel. Power Tunnel begins near sheds in right center 

Priest Regulating Reservoir. Dam at left. Gatehouse in upper right is at entrance to 

Power Tunnel which is 95 feet below high water. Mountain Division Tunnel discharges 

near house in right center, 70 feet below high water 

circular concrete tower of 6 feet inside diameter. The tunnel and tower contain 1954 
cubic yards of concrete. The dam was begun in January, 1922, and completed in 
August, 1923. 

Moccasin Power Tunnel 
Water discharging from the reservoir to the power house enters Moccasin 
Power Tunnel at elevation 2145 through a concrete control tower, oval in plan, 

£/er. z/z&ydaxifiary Ot/t/et Tunnet 
6mdeZZ2Z{ 6'dio., 97J ' /ova,tf?rvi/(?h bed rocA 

/Reinforced concrete 
6a fe Tower 

Sca/e of feet 

fba J of ts.8 mis. tunnet from 
( Ear/y /nfa/re ,£/er. 2//o'. 
^-^Sc]^- / n / et of 


Area inside concrete 

Area of excavation, 
ant/rnbered tjf.9B : 

Excavation per f/'neat 
foot 6..5Z c 

Concrete, -do- t.27 

' , actual average 
for Jt33fi ft. J.So cuyc 







Department w Public Works, approved ^(/CCC-^/A^j^U^O^/ City Cnoineer 

BY. -£*5^.. TRACED. £«*?, . CHECKED .$?M 9 :- 9 " A OO C 

SCALE. As. shown. .. DATE Jrjrie 12, 1925 . /ACO^. 


65 feet by 36 feet, inclusive of semi-circular, precast screen rack projecting into the 
reservoir. The structure contains 2765 yards of 1:2:4 concrete. Six electrically 
operated sluice gates, each 6 feet by 8 feet, provide for cutting off water to the 
tunnel. Manual operation is also possible and steel shutters are provided for 
isolating any set of gates for repairs, if necessary. Fixed screens with manually 
operated cleaner prevent fine trash from entering the tunnel. 

The tunnel begins as the frustum of an oblique cone tapering from about 19 
feet width and height to 13 feet standard section in a distance of 30 feet. The 
tunnel section is 141.47 square feet with grade of 6 feet per 1000, making its 
capacity 1240 second feet without excessive loss of head. The minimum thickness 
of concrete inside of timbering is 9 inches; the concrete averages 3.8 cubic yards per 
lineal foot. The tunnel extends 5370 feet to the inside wall of a surge shaft 40 feet 
in diameter, which serves as a manifold for the three penstock pipes, which are 
imbedded in concrete in tunnels 535 feet long, leading from the opposite side toward 
the power house. 

Surge Shaft 

The surge shaft is designed to handle surges of from 35 to 40 feet. The floor 
is at tunnel grade, elevation 2112, and the height to the rim is 160 feet. It projects 
48 feet above the surface of the ground. The walls of this portion range in thickness 
from 24 inches to 10 inches and contain heavy reinforcement, the maximum of 
which is two rings of 1^2-inch square bars staggered at 7-inch centers. Accumulation 
of external water pressure below the ground surface which might result from 
surface runoff, is prevented by a system of porous cement drain tile. The shaft 
contains 2185 cubic yards of 1:2:4 concrete. 

Penstock Pipes 

The three penstock pipes, the horizontal length of which is 5349 feet, begin at 
the wall of the surge shaft, each as the frustum of an oblique cone with large 
diameter 12 feet 4 inches. The smaller end connects to the 104-inch diameter riveted 
steel pipe. About 50 feet westerly from the tunnel portal in each line a 10+-inch 
diameter butterfly valve has been installed. The most southerly pipe is dead-ended 
at the valve pending future extension when two more generators shall have been 
installed in the power house. The butterfly valves are motor operated and arranged 
for closing by remote control from the power house. As a matter of precaution the 
opening control is at the valve only. Two sets of four 8-inch air valves are installed 
in each line immediately below the valves. 

The thickness of pipe plate at the surge shaft is >^g-inch. At elevation 2070 
the diameter reduces to 98 inches and the double riveted lap joints change to triple 
riveted butt. At a slope distance of 2111 feet the pipes branch each into two 66-inch 
diameter pipes of hammer forge welded steel with "bumped" joints of enlarged section, 
reducing obstruction to stream flow of rivet heads. The welded pipes whose slope 
length is 3469 feet, range in diameter from 66 to 54 inches and in thickness from 
7/16-inch to 1 5/16-inch. Immediately before entering the power house the four 
54-inch diameter pipes branch each into two 36-inch diameter pipes in which are 
installed in an arcade of the power house hydraulically operated 36-inch gate valves. 

The total weight of pipe is 12,487,709 pounds, the heaviest section of pipe weighing 
approximately 26,000 pounds. The 30-foot lengths are supported on some 400 concrete 
piers, or saddles, built in advance of the pipe-laying. At angles, of which there 
are 20, either horizontal, vertical or combined, the pipes are held securely by concrete 
anchors, the largest of which contains 839 cubic yards of concrete and 7.64 tons of 
reinforcing steel. Expansion joints are provided between anchors. At the 98-inch 


by 66-inch "Y" branch is a special sliding anchor in which the upper portion, 
inclosing the pipes, can slide on cast iron plates imbedded in the fixed concrete of 
the lower portion. 

Moccasin Power Plant Penstocks at west end of Power 

Tunnel. In upper center is the surge shaft where the 

tunnel divides and pipes begin 


This power plant, the largest of the Hetch Hetchy system, uses the full flow 
of the aqueduct, 620 second feet, dropping from 2240 feet, the elevation of high 
water in Priest Reservoir, to 924 feet, the elevation of the water wheel nozzles. 

The power house, as at present built for four units, is 225 feet long, 98 feet 
wide and 67 feet high. It is a steel frame building, with massive concrete foundations 
and with reinforced concrete walls. The architecture is of the California-Spanish 
style, which is particularly suited to the site. This building houses the generators 
and low voltage switching apparatus, but the step-up transformers, high tension 
switches and high tension busses are installed in the rear, out-of-doors, at the easterly 
side of the building. The busses are carried on a structural steel frame. The 11,000 


volt, 3-phase, 60-cycle current generated, is stepped up to 115,000 volts for trans- 
mission to San Francisco. All apparatus, however, is designed for operation at 
154,000 volts. 

The water wheels were manufactured by the Pelton Water Wheel Company 
of San Francisco. These are of the double over-hung impulse type and operate at 
257 r.p.m. Each has a rated output of 12,500 h.p., or 25,000 h.p. for the unit. The 
rotating part of each unit weighs 118 tons and can be handled by the 135-ton crane 
installed in the power house. The static pressure head at the power house is 1316 
feet. The water wheel rating is, however, based on an effective head of 1250 feet. 
The maximum jet diameter is 11 inches. An auxiliary relief needle nozzle is set 
directly beneath the main nozzle and connected therewith in such manner that it may 
be operated as a synchronous bypass, or may be set to close automatically to save 

The generators and exciters were furnished by the General Electric Company. 
The rating of the generators is 20,000 K.V.A. These generators deliver 11,000 
volts directly to the transformers, the arrangement of the power house being such 
that so far as practicable the generators and the transformers operate together as a 
unit, provision being made for but one 11,000-volt bus, which can be used to connect 
any generator to any bank of transformers in an emergency. From this 11,000-volt 
bus all auxiliary power is taken for use in the operation of the station, and for two 
22,000-volt circuits for construction work along the aqueduct line. 

The transformers, switchboards and switches were supplied by the Westinghouse 
Electric and Manufacturing Company. The transformers are single phase, 6667 
K.V.A. capacity, with taps which permit of their being operated at either 11,000 to 
115,000 volts, or 11,000 to 154,000 volts. They are set out-of-doors in banks of three; 
complete piping connections are provided for circulating water and for oil filling 
and filtering. Tracks and transfer cars permit of any transformer being moved into 
the power house under the crane for repairs. 

From the switching station behind the power house, two 154,000-volt circuits 
will be carried to San Francisco on one double circuit steel tower line. The 
electric transmission line at the present time has been built as far as Newark on 
San Francisco Bay, a distance of 9% l / 2 miles from the power house; 506 towers are 
employed in this distance — an average spacing of 1,000 feet. They are placed on 
the northerly boundary of a 110-foot right-of-way strip, to be supplemented in the 
future with a similar line on the southerly side. The distance between lines is 24 
feet at the top arm, 28 feet at the middle arm, and 24 feet at the bottom arm. 
The vertical spacing between conductors is 15 feet. The lowest cross-arm is 62 
feet above the ground. The conductors from the power house to a point within a 
few miles of the bay are 397,500 cm. steel reinforced aluminum conductors. From 
the point where bay fog is encountered, hemp cored copper conductors are used. 
These have a circular mil capacity of 345,000, with an external diameter of ^-inch. 
At suspension points, 10 units of Westinghouse No. 601 insulators are used, while at 
dead-end and other points of stress, 12 Westinghouse No. 631 insulators are employed. 

Operation of the present two circuits in parallel, as will normally be the case, 
will permit of transmitting the power generated at the Moccasin plant with a line 
loss of approximately 8 per cent, and when one line must be taken out of commission 
temporarily, the remaining circuit will still have capacity to transmit the output 
of the plant to San Francisco. 



The plan for the aqueduct to San Francisco calls for 17 miles of tunnel in the 
Sierra foothills below Moccasin Creek, the tunnel being divided into two sections at 
the Tuolumne River by the Don Pedro Reservoir at Red Mountain Bar. The 
reservoir is crossed by an inverted steel pipe siphon cased in concrete. This 
construction was not required for several years to come, but as the river channel at 
the crossing was to be flooded by the reservoir constructed by the irrigation districts 
of Turlock and Modesto, the lower portion of the siphon submerged by the lake was 
constructed in advance of filling the reservoir. 

This section, with the ends extending well above the elevation of the dam crest, 
is of riveted steel pipe, 9 feet 6 inches in diameter and 771 feet long. The thickness 
of the steel varies from ^-inch to 9/16-inch. The interior of the pipe is lined with 
cement mortar 2%. inches in thickness, leaving the net diameter 9 feet \y 2 inches. 
The pipe is laid on bedrock and is incased in concrete from 18 inches to 2 feet in 
thickness. The siphon is designed to carry the entire flow of the aqueduct of 400 
million gallons per day. 

A camp accommodating 100 men, and a plant including tramway, bunkers, etc., 
were constructed on the west side of the Tuolumne River near the crossing. 
Excavation was started in the main channel in November, 1922, the water being 
diverted by means of a cofferdam around the work. This section was rushed with 
all possible speed. Early fall rains hampered the work and in December, when 
12,000 second feet of water passed down the river, a small section of the cofferdam 
was washed out. After concreting this first section of pipe, the river was turned 
back into its channel over the pipe and a cofferdam thrown around the east channel. 
No unusual difficulties were encountered on the remainder of the work and the 
siphon was completed and tested on June 1, 1923, in time to permit the Modesto and 
Turlock irrigation districts to close the gates of the Don Pedro Dam and fill the 
reservoir for that season's irrigation. 


A 45-mile steel pipe siphon is to be constructed as the last stage of the project 
across the San Joaquin Valley from Oakdale Portal to Tesla Portal, connecting the 
future Foothill and Coast Range tunnels. To carry the 400 million gallons daily, 
which will be released from Moccasin power house, several pipes will be constructed 
in the future as necessary. 


From Tesla portal to Irvington Gate -House, a distance of 31 miles, a tunnel 
10 feet 3 inches in diameter will be constructed through the Coast Range. It will 
be broken at one point by Alameda Creek, which will be crossed by a pipe line one- 
half mile long. 


The water which San Francisco obtains from east of the bay is now limited to 
about 21 million gallons daily, the capacity flow through one 36-inch pipe. A greater 
supply from the developed sources in Calaveras Valley, east of the bay, will be 
made available by the conduit across Dumbarton Strait and westward to Crystal 
Springs Reservoir. Work now in progress has for its object the construction of a 
part of the Hetch Hetchy aqueduct, which, as previously mentioned, will be used 


temporarily for this purpose by the Spring Valley Water Company immediately 
upon its completion. 


A 5-foot steel pipe line has been built, extending from a junction with the 
Spring Valley Water Company pipe line, near Irvington, to the east end of Pulgas 
Tunnel. The total length of the 5-foot pipe line is 19.4 miles, and the thickness 
varies from 5/16-inch to 7/16-inch. In firm and dry ground the pipe is buried, 
except portions crossing gullies near the west end, which are supported on steel 
trestles resting on concrete piers. Over the marsh lands adjacent to Dumbarton 
Straits, pipe is laid on timber trestles and is protected from the weather by board 

The contract for constructing the pipe line was awarded to the Western Pipe 
and Steel Company of California on May 18, 1923, for an estimated price of 
$2,232,000. Pipe laying was begun on October 20, 1923, and all of the pipe has now 
been laid. 


It was necessary to cross the marsh between Newark and Dumbarton Straits 
for a distance of about three miles and from the west shore of the bay for nearly 
one mile. A pile trestle structure was built which carries the pipe about four feet 
above the surface of the marsh. 

Contract and specifications for this were prepared and bids received on April 30, 
1924. The contract for the construction was awarded to Youdall Construction Com- 
pany for the sum of $167,645. 


Across the shallow portion of Dumbarton Strait the 5-foot diameter pipe is 

^^^r,.-->" »* K>k 

WKKm wa 



r^-^^^'B M mil 

Bay Development. Five-foot diameter pipe on steel bridge on concrete piers 
crossing- of San Francisco Bay at Dumbarton Strait 

now carried on a steel bridge of 36 spans, each 105 feet long, extending from the 
west shore of the bay to a concrete caisson at the eastern terminal. It is designed 
ultimately to carry two pipes, each 6 feet 4 inches inside diameter. 

The contract for the steel superstructure was awarded on August 17, 1923, to 
the United States Steel Products Company, and the contract for the concrete piers 
and caisson on April 1, 1924, to Healy-Tibbits Construction Company. Construction 
is still in progress. 

The cost under the two contracts will be about $1,465,000. 


Two navigable channels are crossed by the Bay Crossing Pipe Line, at Dumbarton 
Strait and Newark Slough. These will be crossed by cast iron pipe 42 inches inside 
diameter and 2 inches thick. The pipe will be laid in a trench so as to be entirely 
below the bottom of the bay, and will have flexible joints every 12 feet. The pipe 
was manufactured by the United States Cast Iron Pipe and Foundry Company. 
In the future, at the east terminal of the bridge, it will be feasible to sink a shaft 
and drive a sub-aqueous tunnel to contain the future greater pipes. 


Near the west shore of Dumbarton Strait a pumping plant has been constructed 
to supplement the pressure at which the water is, at present, delivered to the pipe 
line, sufficiently to deliver it into the Crystal Springs Reservoir, 290 feet elevation, 
through the Pulgas Tunnel. 

The station contains three centrifugal pumps, each driven by a 500 horsepower 
electric motor. With all three pumps operating, the capacity of the pipe line will be 
about 32 million gallons daily. 

When the Bay Crossing Pipe Line is connected with the Hetch Hetchy Water 
Supply, the use of the Dumbarton pumping station will be discontinued, the gravity 
head available at Irvington Gate House being sufficient to give the pipe line a 
capacity of about 42 million gallons daily. 


This tunnel, which forms the westerly end of the aqueduct from Irvington to 
Crystal Springs Reservoir, was completed by Grant Smith and Company in May, 
1924, at a total cost of $738,429.23, or $85.11 per lineal foot. It is 8676 feet long, 
10 feet 3 inches in height and width inside, and is lined with concrete throughout. 
All but 240 feet required timbering. Connection to the two portals is made with 
reinforced concrete pipe 337 feet long. A concrete lined outfall canal 906 feet long, 
9 feet wide, extends from end of tunnel to the edge of the reservoir. 

Plans for the future provide for extending the aqueduct through San Mateo 
County to Amazon Reservoir in San Francisco. 


The present city reservoirs of the water company have a combined capacity of 
125 million gallons, or about three days' domestic water supply, in case the mains 
should be broken. Prudent policy dictates that a storage of at least 1,000 million 
gallons should be maintained within the city limits. It is proposed that three great 
city reservoirs be constructed, known as the Amazon, Glen Park and Balboa Park. 
Land has been purchased on two of these sites. 

Amazon Reservoir, near the county line, in the saddle on the north side of 
Geneva Avenue between Mission Street and Visitacion Valley, will be the terminal 


reservoir of the Hetch Hetchy aqueduct, which will deliver water into it by gravity 
at elevation 250 feet. The capacity of this reservoir will be 300 million gallons or 
greater. A tract of land covering 55^4 acres has been selected for this reservoir 
site and all but 3% acres is already in the possession of the city. 

Glen Park Reservoir site lies in a canyon just below the Twin Peaks Boulevard 
and above the old picnic grounds known as Glen Park. At the lower end of the 
valley there is an excellent bedrock site for a dam of the same general type as the 
Priest Regulating Dam. A dam 150 feet high will provide storage for 500 million 
gallons at elevation 385 feet. Over 109 acres of the 184 acres required is already 
under city ownership. 

Balboa Park Reservoir will be constructed on a tract of land in the possession 
of the Spring Valley Water Company between Balboa Park and Westwood Park, 
north of Ocean Avenue. The site covers 41 acres. A reservoir with 200 million 
gallons of water, at elevation 310 feet, may be constructed here. 

Glen Park and Balboa Park reservoirs will be filled by pumping from Amazon 
Reservoir. It has been decided that the most economical elevation at which to 
receive Hetch Hetchy water in San Francisco is that of the Amazon Reservoir. 
About 45 per cent of the total ultimate amount of water used in the city may be 
distributed from this latter reservoir without pumping. The elevation of Crystal 
Springs Reservoir, 290 feet above the sea, will not permit bringing water by gravity 
at an elevation materially greater than that of the Amazon Reservoir. 

Quality and Quantity of Water. — The water impounded at Hetch Hetchy and 
Lake Eleanor is of the utmost purity and will always remain so. The total area of 
watershed aggregates 652 square miles, or about 420,000 acres, all of granite, ranging 
in elevation from 3500 feet to over 13,000 feet above sea level, and lying almost 
entirely within Yosemite National Park. The precipitation is mostly in the form of 
snow, which accumulates during the winter and spring, and whose thawing by the 
sun's heat reaches its maximum about June. There is no permanent, all-year residence 
on the entire watershed, which is inhabitable only for the three summer months. 

There will be no open canal in the aqueduct, the water being conducted through 
pipes and tunnels for the entire distance. The water will require no filtration, aera- 
tion, chlorination, nor any treatment of any sort. 

The Board of Army Engineers, in 1913, reported that there was sufficient water 
to supply both the reasonable demand of the bay communities and the reasonable 
needs of the Turlock-Modesto Irrigation District for the remainder of this century. 
All water measurements are made by the United States Geological Survey. 

Finances. — The work was financed up to 1909 by appropriations from the 
general tax levy. 

In November, 1908, a bond issue of $600,000 was authorized by the voters, largely 
to buy lands and water rights. 

In January, 1910, a bond issue of $45,000,000 of \ l / 2 per cent bonds was 
authorized. Construction has been carried on by these funds. The bonds sold in 
August to November, 1921, were converted to 5^4 per cent, sustaining a discount 
loss of $2,980,326.55. 

The operating receipts of the Hetch Hetchy railroad and power plant, aggregating 
$1,600,000, have been placed in a special account from which moneys have been 
appropriated by the Finance Committee of the Board of Supervisors to pay interest 
on bonds. 

On October 7, 1924, a bond issue of $10,000,000 was authorized by the people 
by a vote of 20 to 1, to continue the aqueduct construction from Moccasin power 

house to the edge of the San Joaquin Valley and to begin construction of tunnel from 
the westerly edge of the San Joaquin Valley to connect with the Bay Crossing 
pipe line at Irvington. 

In about three years it will be necessary to provide an additional $23,000,000 
to complete this last tunnel and construct the pipe line across the San Joaquin Valley. 

The attitude of the public on the water question was well shown in the elections 
of 1910 and 1924, where the vote was in each case over 20 to 1 in favor of the 


Financed from Bond Issue of 1909 and 1910, and General Fund 

expenditures previous to 1909. 

Hetch Hetchy Division 

O'Shaughnessy Dam, clearing of Hetch Hetchy Reservoir $ 7,400,000.00 

Eleanor Division 

Eleanor Dam, clearing of Lake Eleanor Reservoir 373,000.00 

Mountain Division 
Early Intake Diversion Dam and spillway and headworks 

of aqueduct $ 610,000.00 

Aqueduct tunnels and appurtenances, Early Intake to 

Priest Reservoir (18.84 miles) 10,100.000.00 

Total 10,710,000.00 

Moccasin Division 

Priest Dam and Reservoir $ 930,000.00 

Moccasin Tunnel, from Priest Reservoir to head of penstock 

lines 1,200,000.00 

Penstock lines 2,000,000.00 

Power House Building, dwellings, school, etc 1,200,000.00 

Power House Machinery 1,135,000.00 

Transmission Line, Moccasin to Newark 1,623,000.00 

Total $8,088,000.00 

Foothill Division 
Red Mountain Bar Siphon 262,000.00 

General, Utilities, etc., on Mountain Development 

Sawmill construction and operation $ 556,000.00 

Lower Cherry Power System, construction and operation.... 1,079,000.00 

Hetch Hetchy Railroad, construction and operation 5,379,000.00 

Munn Sand Plant, Groveland Water Supply, etc 77,000.00 

Hospital, construction and operation 221,000.00 

Miscellaneous Structures, Water Supply at Groveland 196,000.00 

Miscellaneous Roads, Trails, Camps, etc 369,000.00 

Boarding House loss 360,000.00 

Field Engineering and Administration 381,000.00 

Total 8,618,000.00 

Total, Mountain Development $35,451,000.00 


Bay Development 

Riveted Steel Pipe Line, 60 inches dia $ 2,408,000.00 

Trestle for Steel Pipe Line 198,000.00 

Submarine Pipe Lines 599,000.00 

Steel Bridge and Piers 1,560,000.00 

Gate Valves, Bay Pulgas Pumps, etc 39,000.00 

Pulgas Tunnel 757,000.00 

Field Engineering and Administration 93,000.00 

City Office Engineering and Administration 42,000.00 

Total 5,696,000.00 


Administration, Engineering, Legal, etc. $ 1,415,000.00 

Reservoir and Watershed Lands, Water Rights, Rights-of- 

Way, Payments to U. S. Government, etc 2,020,000.00 

Lands and Rights-of-Way, San Joaquin Division 215,000.00 

Lands and Rights of Way, Transmission Line 117,000.00 

Lands and Rights-of-Way, Bay Development 221,000.00 

Miscellaneous 322,000.00 

Total 4,310,000.00 

Total Expenditures $45,457,000.00 

Less credit for receipts from operation of Hetch Hetchy Railroad, Lower 

Cherry Power System, lumber sales, etc 1,907,000.00 

Net total expenditures after deducting credits, which may be still further 
reduced on final accounting by salvage value of equipment now 
on hand $43,550,000.00 





S-Xtr77at7 jV 



5 B 

A// ?JJ//72/aH3<i'JG l 

1 I I 

i ; .j 






ua/oivoQ UO/. 

M/C7 u/ett//>ew 


I if 
i s x^ 

z O -1 ^N? „ 

< w < CSS f 
fc ^ t"^ 5 
G OOY?, :. 
ui x •" S " 
5 ^ Q got 
w S z. t s C 

o o< - a u 

i -» » 56 

S- < J e 
= 3 ° i 

» z *d 
5 z y j 

| < 53 

* o- o 

Z J 

* *i 

z o ■ • 


r 1 ! 


1 | 
1 ^ 


' — i -> 
1 ^ 



1 "2. 
1 .^Z. 

r 5 " 


v- \ 

\ h 


1 ***!&* 
I ? S s ? "*> 

fe » ^ ^ ^ ^ p 

!^ 5; £ & ^? ^ ^> 58 
S J5 $ ^ $ $ ^ ^ 

^ J; N N ^ »\ J5 i^ 
^ ^ ^ "\ §• ** § ^ 

e ■ • • 1 • 5 

\ \ 



' 3 ' 





o r/yo/77/^v 

/u 1 / pjwj/c/jJc/xj 

\ ? 



1 « Ms 

1 fo? - • 






2 guj > 

e> t- n z " 1 




^ S 


<^t>? uo/r/s/(j 



s^2 j 



- : > 

1 1 













5 ^R<V' 





1 ? 



. p&^iyfv?**^ 


-r - J 









- § 





° O Q r- S : "1 

5 »o* 5 o- 

r 1 




3 „ 





»; * 






is 1 
§ 1 






1 § " 



ui u o 5 u : 

* Q. - 1 £ J J 
x 0. i»ia 
"3 iu < -J 3 

Ss-nv^oo ")| j "• 
Si a *al ! c 




\/3J Zi 








£ i 2S&I 

S= — ' o o 

C O "i > _* m «-. 
-CM -- ONCM 

^ o r» -a on 

15 -« 

^ <u <u 


r; o o « o 
f ': 'u o no "J -o 

o o -+ 
■ - w os 


— • — 
en £ — 

^ r c 
c <i> — 

Oil ^H 

> c 

< - 

J- — onocoojno—- 

_ 03 vi o o o <m ^ 

Z -Z -+ © o nO_ r- ^ 

S a £ S ~ " «" 


E G 


5 *•§■ 

> o tl 

<u — 

<U o 

c £ 

s P 

a s 

O 03 


■J ° 


13.-- 0. 5 

a -2 
E 5 

o - ;; 03 - 

4J rt 03 vih 

-C HO 

J= J3 £ 

I i I 

aaj?^ c 



o o 



*f ■+ 




o o 

o o 


OhO + 

2^5 S s 

_^ <L> P^O 

H^^ oo o 

D —3 ,-h O O in 

o o 
o o 

o o 





a,^. O o e— P 

— a, £ u .fch 

J S £ ^ § °*'*< u* *< S 



" £ 


"2 >, 

-^ "5 



x *■- 









Jh 3 



u "0 



3 H o 5 — 

*H CO 

o c 

^ K So ^ o 

° 2 
o o 

csf ^o 

o ~ s 

o o — 

O O -2 

o o « 

S re 2 

f,S N ^ 



o o 

°- *j _D — v. W rt 

.5 M 

° « 2 

! £ ^ 

•- (LI 

•- c 

c ^ 
1) 11 

E >> 


o o 

! £* 

"2 a 1-Sl 

zqo £ -? ^ £ go 
£ "*" z 


Jan. 8, 1900 

March 26, 1900 

Aug. 12, 1901 

July 29, 1901 



























May 12, 1910 










25 to 






March 3, 1913 
June 25 to 

July 7, 1913 

Dec. 19, 1913 

July 8, 1914 

July 21, 1915 

September, 1915 

Nov. 24, 1915 

Aug. 9, 1916 

























Aug. 14, 1925 

New Charter in effect. 

Solicitation of offers of sale of water supplies to City. 

City Engineer recommends Tuolumne River. 

Appropriations made on water at Hetch Hetchy and Lake Eleanor 

by Jas. D. Phelan. 
Filings of same at Stockton Land Office. 

Phelan's applications denied by Secretary of Interior Hitchcock. 
Petition for rehearing, by Franklin K. Lane, City Attorney. 
Filings assigned to City. 

Application again denied by Secretary of Interior. 
Original applications approved by Secretary of Interior Garfield. 
Special election authorized construction of Tuolumne System and 

issue of $600,000 of bonds, to buy lands, etc. 
Bond election, $45,000,000 bonds authorized by vote of 20 to 1. 
Order to show cause why Hetch Hetchy should not be eliminated: 

Secretary of Interior Ballinger. 
Secretary of Interior requested Secretary of War to appoint Board 

of Army Engineers to act as Advisory Board. 
Board appointed. 

"Freeman Plan" of Hetch Hetchy development, published and sub- 
mitted to Army Board. 
M. M. O'Shaughnessy appointed City Engineer. 
Hearings before Secretary of Interior Fisher, attended by Mayor, 

City Engineer, City Attorney and consulting engineers. 
Army Board report upholds selection of Tuolumne River as 

$20,000,000 cheaper than any other system and having greatest 

power possibilities. 
Conference: City Engineer with Secretary Fisher. 
Hearings by committee on the Public Lands, House of Repre- 
Hetch Hetchy Grant, or "Raker Bill," signed by President Wilson. 
Bids received by Board of Public Works for Contract No. 1, for 

constructing a road from Hog Ranch (now Mather) to 

Hetch Hetchy. 
Began manufacture of lumber at Canyon Ranch. 
Began construction of camp buildings at Hetch Hetchy, clearing 

of Hetch Hetchy Reservoir site, and construction of Diversion 

Bids received for construction of Hetch Hetchy Railroad. 
Bids received for "Drifting Tunnels, Lower Cherry Aqueduct," 

already begun by day labor. 
Hetch Hetchy Railroad operation begun. 
Lower Cherry Power House began operation. 
Contract awarded for construction of Hetch Hetchy Dam. 
Contract awarded for construction of Aqueduct Tunnels in 

Mountain Division, this work having been carried on so far 

by day labor. 
Work begun on Priest Dam. 
Work begun on Moccasin Power House. 
Contract awarded for construction of Pulgas Tunnel. 
Contract awarded for construction of Bay Crossing Pipe Line. 
Special Election, $10,000,000 bonds authorized to construct Foothill 

Tunnels and begin Coast Range Tunnels, vote 20 to 1. 
Delivery of power began from Moccasin Power Plant. 



13,090 ft. Summit of Mt. Lyell, highest point on watershed. 

4,825 ft. Crest of future Lake Eleanor Dam. 

4,810 ft. High water, Lake Eleanor Dam. 

4,660 ft. Top of present Lake Eleanor Dam. 

4,590 ft. Creek bed at Lake Eleanor Dam. 

3,812 ft. Crest of future O'Shaughnessy Dam. 

3,726.5 ft. Crest of present O'Shaughnessy Dam. 

3,500 ft. River bed at O'Shaughnessy Dam. 

3,382 ft. Lowest point of foundation, O'Shaughnessy Dam. 

2,346 ft. Normal water surface, Early Intake Diversion Dam. 

2,326 ft. Floor of tunnel, Early Intake Diversion Dam. 

2,240 ft. High water, Priest Regulating Reservoir. 

2,170 ft. Floor of tunnel at Priest Portal of 18.8-mile tunnel. 

2,145 ft. Floor of inlet of Moccasin Power Tunnel. 

924 ft. Nozzles of Moccasin Power House. 

888 ft. Floor of Foothill Division Tunnel at Moccasin Creek. 

741.6 ft. Floor of Foothill Division Tunnel at Oakdale Portal. 

360 ft. Floor of Mt. Diablo Range Tunnel at Tesla Portal. 

321 ft. Floor of Mt. Diablo Range Tunnel at Irvington Gate House. 

290.5 ft. Floor of Pulgas Tunnel at Redwood Portal. 

250 ft. Water surface, Amazon Reservoir, San Francisco. 




Ccficnfy 7/.0C0aXMga/s 

a 4 550 ■Capou/ !/ /4S&WX>ftfi 

7 /i,/mB 3300' 

Wafer from fVefcn fre/cny Pes. m/l ' fbir 
■ fo For/t/ Intake ant// demand 
far porrer trarranfs construct/on of 
Canyon Dirrsion of ' aoaedacf 

x Construe/run PonerPtanf (loner Ctierru) 3300 tf)t 









4// eteyofrons refer fo f/etch ttetc fy fofi/r?. nfo'c/r /s epprosmifet/ 
/Htfe/ ciore VJ6S Do/am an/ 7 73 fee/ ie/an SfCfy fo/um 





!OVED_'^^^ ! ^^^^fet/ut s ^--__CITY ENGI! 

JANUARY * 1925 

^1925 '